Multivitamin use doesn't impact colon cancer outcomes, study finds
Kimmie Ng, MD, MPH
Patients with colon cancer who used multivitamins during and after
being treated with post-surgical chemotherapy did not reduce the risk of
the cancer returning or their dying from it, according to researchers
at Dana-Farber Cancer Institute.
In a study of patients with stage III colon cancer — characterized as
cancer in the large bowel area with some cancer cells in a few nearby
lymph nodes — the researchers found that while multivitamin use had no
beneficial effect on patients' outcomes, it also did not have a
detrimental effect.
The findings are reported online in the Journal of Clinical Oncology and later will be published in a print edition.
Kimmie Ng, MD, MPH,
the paper's first author and a gastrointestinal oncologist at
Dana-Farber, said that despite conflicting evidence on the efficacy of
multivitamins to reduce cancer risk and death, studies suggest that
approximately 30 percent of Americans take multivitamins to prevent and
treat chronic diseases such as cancer.
Among cancer survivors, between 26 and 77 percent report using multivitamins.
"With such a high proportion of cancer patients utilizing
multivitamin supplements in the belief that it will help them fight
their cancer, we felt it was important to really examine the data to see
what impact multivitamins had on cancer recurrence and survival," said
Ng.
The researchers used two questionnaires to track multivitamin use during and after chemotherapy.
Of the 1,038 patients who completed the first survey, nearly half
(518) responded they used multivitamins while receiving chemotherapy.
Of the 810 cancer-free patients who completed the second survey six
months after chemotherapy, more than half (416) reported multivitamin
use.
Ng and her colleagues found no statistically significant differences
in the rates of disease-free survival (the study's primary endpoint),
recurrence-free survival, or overall survival between those who used
multivitamins and those who didn't.
They also determined that an array of factors, including
socio-economic status, household income, multivitamin and individual
vitamin dosage, and consistency of multivitamin use did not impact their
findings.
However, they did find a small beneficial association between age and
weight and the use of multivitamins while receiving chemotherapy.
Those 60 and younger experienced some survival benefit, as did obese
patients. There were no benefits for either subgroup when the
multivitamins were taken after chemotherapy was completed.
Ng said additional studies are needed to confirm their findings and
to investigate whether there were other factors that influenced the
outcomes.
"This study adds to a growing body of research that questions the
purported benefit of multivitamin use, and it underscores the need to
investigate the use of individual vitamins, such as vitamin D, which
may, in fact, provide real benefit," said Charles Fuchs, MD, director of
gastrointestinal oncology at Dana-Farber and the paper's senior author.
He noted that the average multivitamin typically contains only a small to modest amount of vitamin D.
The study was funded in part by the National Cancer Institute and by
an American Society of Clinical Oncology Young Investigator Award.
In addition to Ng and Fuchs, the other authors are Jeffrey A. Meyerhardt, MD, MPH, Jennifer Chan, MD, and Robert J. Mayer, MD,
Dana-Farber; Donna Niedzwiecki, PhD, and Donna R. Hollis, BS, Duke
University; Leonard Saltz, MD, Memorial Sloane Kettering Cancer Center;
Al B. Benson, III, MD, Lurie Comprehensive Cancer Center, Chicago; Paul
L. Schaefer, MD, Toledo Community Hospital Oncology Program, Toledo, OH;
Renaud Whittom, MD, Hôpital du Sacré-Coeur de Montréal; Alexander
Hantel, MD, Edward Cancer Center, Naperville, IL; and Richard M.
Goldberg, UNC Lineberger Comprehensive Cancer Center, Chapel Hill, N.C.